In order to manufacture advanced materials such as semiconductor devices, water which is substantially free of impurities and particularly organic impurities is often required. For example, in the process of manufacturing integrated circuit chips, one of the key steps therein is the cleaning process following chemical etching of the semiconductor wafer. The cleaning process includes rinsing the wafers in deionized water and drying the wafers by passing an inert gas over the wafers. The rinse process can require 9-12 rinses and over 2,000 gallons of water when etching multiple wafers. The cleanliness of the rinse water is critical to the performance characteristics of the semiconductor device. Even trace amounts on the parts per billion (ppb) level of contaminants, although often undetectable, can adversely effect the performance characteristics of the semiconductor device. Typically, the water must be purified "ultrapure" water. The purity is closely monitored by measuring resistivity, total organic carbon (TOC) and/or particulate count. For example, less than 50 ppb TOC level is desirable for use in manufacturing semiconductor devices.
Conventional treatment systems for ultrapurifying water use 185 nm ultraviolet (UV) light, ozone or reverse osmosis and combinations thereof (see, for example, U.S. Pat. No. 5,061,374 to Lewis). For example, UV treatment is often conducted by passing the water to be purified by a UV source which irradiates the water with 185 nm UV light. The problem with such systems is that the UV radiation tends to leak due to reflections out of the UV treatment unit. The leakage adversely affects the various polymeric materials used as piping and components connected to the UV treatment unit. The degradation and breakage of the polymeric parts is an additional source of organic contamination, particularly over prolonged exposure to the UV radiation. To minimize these problems, elbows and valves are sometimes placed at the inlet and outlet of the UV treatment unit to reduce direct exposure of the polymeric parts to the UV radiation. These techniques are typically ineffective and can also become additional sources of contamination.